Sediment microbiota as a proxy of environmental health along the Eastern Mediterranean coastal shelf

Marine sedimentary habitats form the largest ecosystem on earth and the sediment microbiota are first and foremost responsible for biogeochemical activity in this system. The accumulative nature of marine sediment on the one hand, and the rapid response of microorganisms to changes in conditions on theother hand, led us to hypothesize that sediment microbiota may qualify as a bioindicator of marine environment health. We therefore aimed to a) resolve environmental drivers of microbiota assembly in marine sediment and b) examine the applicability of sediment microbiota as a reference model forenvironmental changes and health.Our study focused on the continental shelf of the South-Eastern Mediterranean Sea. A region of unique properties, classified as ultra-oligotrophic and suffering many acute and chronic disturbances of anthropogenic source. We have curated data covering three years of sediment sampling. Our main finding was our sediment microbiota model was robust, in terms of both representation of region (outside the model sites), identified biomarkers and detection of disturbance. These results are significant for both basic understanding of marine sediment microbiota assembly, and as proof-of-concept for future long-term marine health monitoring. Importantly, we demonstrate that integration of information derived from the three kingdoms- Archaea, Bacteria and Eukaryota is key to understanding environmental factors effects on microbiota composition and ecological processes involved in microbiota assembly.We consider the study and its findings to be of wide appeal, first based on their contribution to the understanding of community assembly in the marine sediment environment. Second, we demonstrates the importance of cross-kingdom integration of information in the study of microbial community ecology.Finally, the urgent need to propose applicable models for environmental health monitoring is addressed here by establishment of sediment microbiota as a robust and sensitive model.